The right of criminal defendants to confront the witnesses against them is one of our most cherished constitutional protections. Yet the meaning and scope of the right have never been clearly defined by the Supreme Court. In 2004, the Court rejected earlier interpretations of the Sixth Amendment Confrontation Clause as vague and uncertain. It unmoored the constitutional question from the hearsay exceptions and replaced the old test with a new one, which has turned out to be quite clear in some areas, but maddeningly uncertain in others: A statement will be excluded if it is “testimonial.” In later cases, the Court explained that a statement is testimonial if its “primary purpose” is to assist in gathering facts for use in a future criminal prosecution.

The primary purpose test for determining whether interactions between government agents and hearsay declarants are testimonial has caused confusion for courts, commentators, and law enforcement officers — not to mention provoking perhaps the nastiest dissent in recent memory. Just last year, in 2012, the Supreme Court once again attempted to clarify primary purpose, but only managed to further confuse the doctrine when the Justices’ opinions split 4-1-4.

In this Article, we propose a method for applying the primary purpose test in a law-enforcement context that increasingly includes multifunction agencies whose duties may be only tangentially connected to the investigation and prosecution of crime.

We propose that the primary purpose of an interaction should be determined, in part, by a statistical evaluation of the relative likelihood of criminal prosecution among the various possible outcomes of a particular category of agent-witness interactions. We then demonstrate how this approach would apply in several situations, particularly those involving the United States Border Patrol — the epitome of a modern multifunction agency with mixed civil and criminal enforcement duties.